Submerged combustion melter comprising a melt exit structure designed to minimize impact of mechanical energy, and methods of making molten glass

ABSTRACT

A melter apparatus includes a floor, a ceiling, and a wall connecting the floor and ceiling at a perimeter of the floor and ceiling, a melting zone being defined by the floor, ceiling and wall, the melting zone having a feed inlet and a molten glass outlet positioned at opposing ends of the melting zone. Melter apparatus include an exit end having a melter exit structure for discharging turbulent molten glass formed by one or more submerged combustion burners, the melter exit structure fluidly and mechanically connecting the melter vessel to a molten glass conditioning channel. The melter exit structure includes a fluid-cooled transition channel configured to form a frozen glass layer or highly viscous glass layer, or combination thereof, on inner surfaces of the fluid-cooled transition channel and thus protect the melter exit structure from mechanical energy imparted from the melter vessel to the melter exit structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of pending U.S. application Ser. No.13/458,211, filed Apr. 27, 2012, which is hereby incorporated byreference herein.

BACKGROUND INFORMATION

Technical Field

The present disclosure relates generally to the field of combustionfurnaces and methods of use, and more specifically to improved submergedcombustion melters and methods of use in producing molten glass.

Background Art

In submerged combustion glass melting, combustion gases are injectedbeneath the surface of the molten glass and rise upward through themelt. The glass is heated at a high efficiency via the intimate contactwith the combustion gases. The melter exit may be connected to aconditioning channel. Using submerged combustion burners producesviolent turbulence of the molten glass and results in a high degree ofmechanical energy in the submerged combustion melter that, withoutmodification, is undesirably transferred to the conditioning channel.Given that long life is a goal for submerged combustion melters andconditioning channels attached thereto, this transference of mechanicalenergy from the melter to the conditioning channel is a significantdetriment to that goal. While transference of mechanical energy from themelter to the conditioning channel is a detriment, and could beeliminated entirely if the melter were physically decoupled from theconditioning channel, it is also desired that the heat contained in thesubmerged combustion melter be fully or nearly fully transferred to theconditioning channel. So in some respects these two goals are at odds,presenting a challenge to operators of submerged combustion melters notpresent in conventional melters (i.e., not a submerged combustionmelter).

U.S. Pat. No. 6,178,777 discloses a conventional, non-submergedcombustion glass melter having a water-cooled throat, and U.S. Pat. No.4,349,376 discloses a conventional, non-submerged combustion glassmelter having a water-cooled skimmer. As neither of these referencesdiscloses submerged combustion melters, the problem of mechanical energytransfer from the highly turbulent melter to the conditioning channel islargely non-existent. In fact, due to the significantly less turbulentconditions of conventional glass melters, conditioning may actuallybegin in the glass melter.

It would be a significant advance in the glass melting art to developmelter exit structures between submerged combustion melter vessels andconditioning channels that are able to reduce or substantially eliminatethe transference of mechanical energy from the submerged combustionmelter vessel to the conditioning channel, while maintaining a minimalglass temperature drop for the glass flowing between the submergedcombustion melter and the conditioning channel.

SUMMARY

In accordance with the present disclosure, melters and methods of usingthem are described that reduce or eliminate transference of mechanicalenergy from the submerged combustion melter to the conditioning channel,while maintaining or increasing heat transfer between the submergedcombustion melter and the conditioning channel. The apparatus andmethods described herein are relevant to the full range of materialsthat could be melted with submerged combustion technology.

A first aspect of this disclosure is a melter apparatus comprising:

a melter vessel comprising floor, a ceiling, a wall connecting the floorand ceiling at a perimeter of the floor and ceiling, wherein at leastsome of the wall comprises fluid-cooled panels, a melting zone beingdefined by the floor, ceiling and wall, and a plurality of burners(air-fuel and/or oxy-fuel burners), at least some of which arepositioned to direct combustion products into the melting zone under alevel of molten glass in the melting zone and form a turbulent moltenglass imparting mechanical energy to the melter vessel, the meltervessel comprising a batch feeder attached to the wall or ceiling abovethe level, and an exit end comprising a melter exit structure fordischarging the molten glass, the melter exit structure fluidly andmechanically connecting the melter vessel to a molten glass conditioningchannel,

wherein the melter exit structure comprises a fluid-cooled transitionchannel configured to form a frozen glass layer or highly viscous glasslayer, or combination thereof, on inner surfaces of the fluid-cooledtransition channel and thus protect the melter exit structure from themechanical energy imparted from the melter vessel to the melter exitstructure.

A second aspect of this disclosure is a melter apparatus comprising:

a melter vessel comprising floor, a ceiling, a wall connecting the floorand ceiling at a perimeter of the floor and ceiling, wherein at leastsome of the wall comprises fluid-cooled panels, a melting zone beingdefined by the floor, ceiling and wall, and a plurality of burners(air-fuel and/or oxy-fuel burners), at least some of which arepositioned to direct combustion products into the melting zone under alevel of molten glass in the melting zone and form a turbulent moltenglass imparting mechanical energy to the melter vessel, the meltervessel comprising a batch feeder attached to the wall or ceiling abovethe level, and an exit end comprising a melter exit structure fordischarging the molten glass, the melter exit structure fluidly andmechanically connecting the melter vessel to a molten glass conditioningchannel;

wherein the melter exit structure comprises a fluid-cooled transitionchannel configured to form a frozen glass layer or highly viscous glasslayer, or combination thereof, on inner surfaces of the fluid-cooledtransition channel and thus protect the melter exit structure from themechanical energy imparted from the melter vessel to the melter exitstructure;

the melter apparatus further comprising a fluid-cooled skimmerconfigured to form a frozen glass layer or highly viscous glass layer,or combination thereof, on outer surfaces thereof, the skimmer extendingdownward from the ceiling of the melter vessel and positioned upstreamof the fluid-cooled transition channel, the skimmer having a lowerdistal end defining a top of a throat of the melter vessel, the throatconfigured to control flow of molten glass from the melter vessel intothe melter exit structure.

A third aspect of this disclosure is a method comprising:

-   -   a) feeding at least one partially vitrifiable material into a        feed inlet of a melting zone of a melter vessel comprising a        floor, a ceiling, and a wall connecting the floor and ceiling at        a perimeter of the floor and ceiling, the melter vessel        comprising a batch feeder attached to the wall or ceiling and an        exit end comprising a melter exit structure for discharging        molten glass, the melter exit structure fluidly and mechanically        connecting the melter vessel to a molten glass conditioning        channel;    -   b) heating the at least one partially vitrifiable material with        at least one air-fuel and/or oxy-fuel burner directing        combustion products into the melting zone under a level of the        molten glass in the zone, and forming the turbulent molten glass        while imparting mechanical energy to the melter vessel;    -   c) discharging molten glass from the melter vessel through a        fluid-cooled transition channel of the melter exit structure;        and    -   d) cooling the fluid-cooled transition channel sufficiently to        form a frozen glass layer or highly viscous glass layer, or        combination thereof, on inner surfaces of the fluid-cooled        transition channel thus protecting the melter exit structure        from the mechanical energy imparted from the melter vessel to        the melter exit structure.

Melter apparatus and methods of this disclosure will become moreapparent upon review of the brief description of the drawings, thedetailed description of the disclosure, and the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The manner in which the objectives of the disclosure and other desirablecharacteristics can be obtained is explained in the followingdescription and attached drawings in which:

FIGS. 1, 3, and 5, are vertical sectional views, of three melterembodiments in accordance with the present disclosure;

FIGS. 2, 4, and 6 are perspective views of the sectional views of themelter embodiments illustrated in FIGS. 1, 3, and 5, respectively;

FIG. 7 is a perspective view of one cooled panel useful in melters ofthe present disclosure; and

FIGS. 8, 9 and 10 are logic diagrams illustrating three methods inaccordance with the present disclosure.

It is to be noted, however, that the appended drawings are not to scaleand illustrate only typical embodiments of this disclosure, and aretherefore not to be considered limiting of its scope, for the disclosuremay admit to other equally effective embodiments.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of various melter apparatus and process embodiments inaccordance with the present disclosure. However, it will be understoodby those skilled in the art that the melter apparatus and processes ofusing same may be practiced without these details and that numerousvariations or modifications from the described embodiments may bepossible which are nevertheless considered within the appended claims.All U.S. published patent applications and U.S. patents referencedherein are hereby explicitly incorporated herein by reference. In theevent definitions of terms in the referenced patents and applicationsconflict with how those terms are defined in the present application,the definitions for those terms that are provided in the presentapplication shall be deemed controlling.

“Submerged” as used herein means that combustion gases emanate fromburners under the level of the molten glass; the burners may befloor-mounted, wall-mounted, or in melter embodiments comprising morethan one submerged combustion burner, any combination thereof (forexample, two floor mounted burners and one wall mounted burner). As usedherein the term “combustion gases” means substantially gaseous mixturesof combusted fuel, any excess oxidant, and combustion products, such asoxides of carbon (such as carbon monoxide, carbon dioxide), oxides ofnitrogen, oxides of sulfur, and water. Combustion products may includeliquids and solids, for example soot and unburned liquid fuels.

The phrase “turbulent molten glass imparting mechanical energy to themelter vessel” means that during submerged combustion, the molten glassis very turbulent, sometimes extraordinarily so. This high degree ofturbulence can increase the mechanical load on the melter vessel wallssignificantly, especially in embodiments where the walls arefluid-cooled, as fluid-cooled wall structures may be made thinner thannon-cooled walls since the frozen or highly viscous glass layer protectsthe walls better than non-cooled walls. Therefore, while there may besavings in cost of materials for submerged combustion melter vesselswith thinner, fluid-cooled walls, and fuel savings due to better heattransfer to the melt, there may be adverse physical impacts on themelter structure due to the very high turbulence imparted duringsubmerged combustion.

The term “air-fuel burner” means a combustion burner that combusts oneor more fuels with only air, while the term “oxy-fuel burner” means acombustion burner that combusts one or more fuels with either oxygenalone, or employs oxygen-enriched air, or some other combination of airand oxygen, including combustion burners where the primary oxidant isair, and secondary and tertiary oxidants are oxygen. Burners may becomprised of metal, ceramic, ceramic-lined metal, or combinationthereof. “Air” as used herein includes ambient air as well as gaseshaving the same molar concentration of oxygen as air. “Oxygen-enrichedair” means air having oxygen concentration greater than 21 mole percent.“Oxygen” includes “pure” oxygen, such as industrial grade oxygen, foodgrade oxygen, and cryogenic oxygen. Oxygen-enriched air may have 50 molepercent or more oxygen, and in certain embodiments may be 90 molepercent or more oxygen. Oxidants such as air, oxygen-enriched air, andpure oxygen may be supplied from a pipeline, cylinders, storagefacility, cryogenic air separation unit, membrane permeation separator,or adsorption unit.

The term “fuel”, according to this disclosure, means a combustiblecomposition (either in gaseous, liquid, or solid form, or any flowablecombination of these) comprising a major portion of, for example,methane, natural gas, liquefied natural gas, propane, atomized oil,powders or the like. Fuels useful in the disclosure may comprise minoramounts of non-fuels therein, including oxidants, for purposes such aspremixing the fuel with the oxidant, or atomizing liquid fuels.

At least some of the burners may be floor-mounted, and in certainembodiments the floor-mounted burners may be positioned in one or moreparallel rows substantially perpendicular to a longitudinal axis of themelter. In certain embodiments, the number of floor-mounted burners ineach row may be proportional to width of the melter. In certainembodiments the depth of the melter may decrease as width of the melterdecreases. In certain other embodiments, an intermediate location maycomprise a constant width zone positioned between an expanding zone anda narrowing zone of the melter, in accordance with assignee's U.S.patent application Ser. No. 12/817,754, filed Jun. 17, 2010, publishedas US 2011/0308280 on Dec. 22, 2011, now U.S. Pat. No. 8,769,992 issuedJul. 8, 2014.

At least some of the burners may be oxy-fuel burners. In certainembodiments the oxy-fuel burners may comprise one or more submergedoxy-fuel combustion burners each having co-axial fuel and oxidant tubesforming an annular space there between, wherein the outer tube extendsbeyond the end of the inner tube, as taught in U.S. Pat. No. 7,273,583.In certain other embodiments the oxy-fuel burners may comprise one ormore adjustable flame submerged oxy-fuel combustion burners as taught inassignee's U.S. patent application Ser. No. 13/268,028 filed Oct. 7,2011, now U.S. Pat. No. 8,875,544 issued Nov. 4, 2014.

In certain embodiments, the melter apparatus may have a floor size for agiven throughput of 2 ft²/stpd or less, and in certain embodiment mayhave a floor size for a given throughput of 0.5 ft²/stpd or less, where“stpd” means “short tons per day.” Stated differently, in certainembodiments, the methods herein may comprise discharging at least 0.5short tons per day per square foot of melter floor, and in certainexemplary processes, at least 2 short tons per day per square foot ofmelter floor.

The term “fluid-cooled” means cooling using gaseous, liquid, orcombination thereof, heat transfer media. In certain exemplaryembodiments, wherein the melter wall comprises fluid-cooled panels, thewall may comprise a refractory liner at least between the panels and themolten glass.

Certain exemplary apparatus and methods may comprise cooling variouscomponents using fluid-cooled refractory panels and directing a heattransfer fluid through the panels. In certain embodiments, therefractory cooled-panels comprising the walls, the fluid-cooled skimmer,the fluid-cooled dam, and the walls of the fluid-cooled transitionchannel may be cooled by a heat transfer fluid selected from the groupconsisting of gaseous, liquid, or combinations of gaseous and liquidcompositions that functions or is capable of being modified to functionas a heat transfer fluid. Different cooling fluids may be used in thevarious components, or separate portions of the same cooling compositionmay be employed in all components. Gaseous heat transfer fluids may beselected from air, including ambient air and treated air (for airtreated to remove moisture), inert inorganic gases, such as nitrogen,argon, and helium, inert organic gases such as fluoro-, chloro- andchlorofluorocarbons, including perfluorinated versions, such astetrafluoromethane, and hexafluoroethane, and tetrafluoroethylene, andthe like, and mixtures of inert gases with small portions of non-inertgases, such as hydrogen. Heat transfer liquids may be selected frominert liquids, which may be organic, inorganic, or some combinationthereof, for example, salt solutions, glycol solutions, oils and thelike. Other possible heat transfer fluids include steam (if cooler thanthe oxygen manifold temperature), carbon dioxide, or mixtures thereofwith nitrogen. Heat transfer fluids may be compositions comprising bothgas and liquid phases, such as the higher chlorofluorocarbons.

Referring now to the figures, FIGS. 1, 3, and 5, are vertical sectionalviews, of three melter apparatus embodiments in accordance with thepresent disclosure, while FIGS. 2, 4, and 6 are perspective views of thesectional views of the melter embodiments illustrated in FIGS. 1, 3, and5, respectively. The same numerals and symbols are used for the same orsimilar features in the various figures. In the perspective viewsillustrated in FIGS. 2, 4, and 6, it will be understood in each casethat some components are not illustrated in order to illustrate moreclearly the key features of each embodiment. Melter apparatus embodiment1 of FIGS. 1 and 2 comprises a floor 2, a roof or ceiling 4, a feed endwall 6A, a first portion of an exit end wall 6B, and a second portion ofthe exit end wall 6C. Each of floor 2, roof 4, and walls 6A, 6B, and 6Ccomprise a metal shell 17 and a refractory panel 9, some or all of whichmay be fluid-cooled. Feed end wall 6A and exit end wall portion 6B mayform angles “α” and “β”, respectively, with respect to floor 2, asindicated. Angles α and β may be the same or different, and generallymay range from about 30 degrees to about 90 degrees, or from about 45degrees to about 75 degrees. Decreasing these angles beyond these rangesmay require more floor space for the melters, and/or more material ofconstruction, both of which are generally undesirable. Increasing theseangles may promote dead spaces in corners, which is also undesirable.Exit end wall portion 6C may form an angle “γ” with respect to skimmer18. Angle γ may be the range from 0 to about 70 degrees, or from about30 degrees to about 75 degrees. Increasing this angle beyond theseranges may require more floor space for the melters, and/or morematerial of construction, both of which are generally undesirable.Decreasing this angle may promote escape of unmelted or melted materialup stack 8, or deposition onto internal surfaces of stack 8, both ofwhich are also undesirable. A frozen and/or highly viscous glass layeror layers 16 may be formed on the inside surfaces of walls 6A, 6B, dueto the use of fluid-cooled panels for these walls.

Melter apparatus embodiment 1 further includes an exhaust stack 8, andopenings 10 for floor-mounted submerged combustion burners 12, whichcreate during operation a highly turbulent melt indicated at 14. Highlyturbulent melt 14 may have an uneven top surface 15 due to the nature ofsubmerged combustion. An average level 7 is illustrated with a dashedline. In certain embodiments, burners 12 are positioned to emitcombustion products into molten glass in the melting zone 14 in afashion so that the gases penetrate the melt generally perpendicularlyto floor 2. In other embodiments, one or more burners 12 may emitcombustion products into the melt at an angle to floor 2, where theangle may be more or less than 45 degrees, but in certain embodimentsmay be 30 degrees, or 40 degrees, or 50 degrees, or 60 degrees, or 70degrees, or 80 degrees.

The initial raw material can be introduced into melter apparatus 1 on abatch, semi-continuous or continuous basis. In some embodiments, a port5 is arranged at end 6A of melter apparatus 1 through which the initialraw material is introduced by a feeder 34. In some embodiments a “batchblanket” 36 may form along wall 6A, as illustrated. Feed port 5 may bepositioned above the average glass melt level, indicated by dashed line7. The amount of the initial raw material introduced into melterapparatus 1 is generally a function of, for example, the capacity andoperating conditions of melter apparatus 1 as well as the rate at whichthe molten material is removed from melter apparatus 1.

The initial raw material may include any material suitable for formingmolten glass such as, for example, limestone, glass, sand, soda ash,feldspar and mixtures thereof. In one embodiment, a glass compositionfor producing glass fibers is “E-glass,” which typically includes 52-56%SiO₂, 12-16% Al₂O₃, 0-0.8% Fe₂O₃, 16-25% CaO, 0-6% MgO, 0-10% B₂O₃, 0-2%Na₂O+K₂O, 0-1.5% TiO₂ and 0-1% F₂. Other glass compositions may be used,such as those described in assignee's published U.S. application20080276652. The initial raw material can be provided in any form suchas, for example, relatively small particles.

As noted herein, submerged combustion burners may produce violentturbulence of the molten glass and may result in a high degree ofmechanical energy (denoted schematically by the symbol “V” for“vibration” in FIGS. 1-6) in the submerged combustion melter that,without modification, is undesirably transferred to the conditioningchannel. Vibration may be due to one or more impacts from sloshing ofmolten glass, pulsing of the submerged combustion burners, popping oflarge bubbles above submerged burners, ejection of molten glass frommain glass melt against the walls and ceiling of melter, and the like.Melter apparatus of the present disclosure have one or more featuresthat attempt to preserve the benefits of submerged combustion, whiledecreasing some of the perceived or actual disadvantages. One importantaspect of melter apparatus embodiment 1 is provision of a melter exitstructure 28 for discharging the molten glass. Melter exit structure 28is positioned generally downstream of melter exit ends 6B, 6C asillustrated of FIGS. 1 and 2, and fluidly and mechanically connects themelter vessel to a molten glass conditioning channel or other structure(not illustrated), such as a distribution channel, forehearth, and thelike. Melter exit structure 28 comprises a fluid-cooled transitionchannel 30, having generally rectangular cross-section in embodiment 1,although any other cross-section would suffice, such as hexagonal,trapezoidal, oval, circular, and the like. Regardless of cross-sectionalshape, fluid-cooled transition channel 30 is configured to form a frozenglass layer or highly viscous glass layer, or combination thereof, oninner surfaces of fluid-cooled transition channel 30 and thus protectmelter exit structure 28 from the mechanical energy imparted from themelter vessel to melter exit structure 28.

As illustrated schematically in FIG. 2, melter exit structure 28 may incertain embodiments comprise an essentially rectangular, fluid-cooled,ceramic or metallic box having a length L, a width W, a height H. Inthese embodiments, length L may range from about 5 to about 50 percent,or from about 10 to about 40 percent, of the entire length of the melterapparatus. The width W of melt exit structure 28 may be the same as thewidth of the melter apparatus (as illustrated in FIG. 2), or may be lessor more than the width of the melter apparatus. The height H may rangefrom about 5 to about 50 percent, or from about 10 to about 40 percent,of the entire height of the melter apparatus, measured from floor 2 toceiling 4. Melter length, width and height depend primarily on theamount of raw material to be fed, the amount of molten glass to beproduced, and the desired throughputs mentioned herein.

Another important aspect of melter apparatus embodiment 1 is provisionof a fluid-cooled skimmer 18 extending downward from the ceiling of themelter vessel and positioned upstream of fluid-cooled transition channel30. Fluid-cooled skimmer 18 has a lower distal end 20 extending adistance L_(s) ranging from about 1 inch to about 12 inches (from about2.5 cm to about 30 cm) below the average melt level 7. Fluid-cooledskimmer 18 may be configured to form a frozen glass layer or highlyviscous glass layer, or combination thereof, on its outer surfaces.Skimmer lower distal end 20 defines, in conjunction with a lower wall ofmelter exit structure 28, a throat 31 of the melter vessel, throat 31configured to control flow of molten glass from the melter vessel intomelter exit structure 28. Preferably, the throat 31 is arranged belowaverage melt level 7. Molten material can be removed from melter exitstructure 28 on a batch, semi-continuous basis or continuous basis. Inan exemplary embodiment, the molten material continuously flows throughthroat 31 and generally horizontally through melter exit structure 28,and is removed continuously from melter exit structure 28 to aconditioning channel (not illustrated). Thereafter, the molten materialcan be processed by any suitable known technique, for example, a processfor forming glass fibers.

Yet another important aspect in certain embodiments is the provision ofan overlapping refractory material layer 32 on at least the innersurface of fluid-cooled transition channel 30 that are exposed to moltenmaterial. In certain embodiments the overlapping refractory material maycomprise a seamless insert of dense chrome, molybdenum, or other denseceramic or metallic material. The dense chrome or other refractorymaterial may be inserted into the melter exit structure and provides aseamless transition from the melter vessel to a conditioning channel orother structure (not illustrated).

Another feature of melter apparatus embodiment 1 is the provision of afluid-cooled dam opening 22 in the upper wall or ceiling of melt exitstructure 28. Dam opening 22 accommodates a movable, fluid-cooled dam24, which is illustrated schematically in FIG. 1 in a retractedposition. Dam 24 may be manipulated by a prime mover 26, such as one ormore motors, jack screws, or the like. Fluid-cooled dam 24 comprisesdimensions allowing the dam to be extended an entire distance from topto bottom of fluid-cooled transition channel 30 and completely isolatethe melting zone of the melter vessel from the conditioning channel.

FIGS. 3-6 illustrate further embodiments and features of melterapparatus of this disclosure. FIGS. 3 and 4 illustrate schematically amelter apparatus embodiment 40, and illustrates that skimmer 18 mayextend substantially more into the melt than skimmer 18 in embodiment 1.In embodiment 40, skimmer 18 is positioned a distance L₂ from the exitof melter exit structure 28. L₂ is greater than the length L₁, which isthe length of the lower wall of melter exit structure 28. The absolutedimensions of L₁ and L₂ are not critical except that L₂ must be greaterthan L₁. For example, L₂ may be twice that of L₁, or L₂ may be 1.5 timesthat of L₁. The ratio of length L₂ and L₁ will also depend on angle “β.”In melter apparatus embodiment 40, skimmer 18 extends downwardlysubstantially in line with a downstream wall of stack 8 such that lowerdistal end 20 forms a submerged throat 31 with end wall portion 6B.Lower distal end 20 may extend sufficiently low so that submerged throat31 is positioned roughly in the lowest one third of the molten bath, oreven in the lowest one fourth or lowest one eighth portion of the moltenbath. This submerged throat position forces the melt generally in thelower regions of the melter apparatus 50 to exit prior to molten glassin the upper or even the middle regions of the apparatus. Further, themolten glass travels generally vertically through a generally lessturbulent zone 35 after passing through throat 31, and then generallyhorizontally through and out of melter exit structure 28. By submergingthroat 31 in embodiment 50, there is a reduction of the transfer ofmechanical energy from the melter to the conditioning channel.

FIGS. 5 and 6 illustrate schematically another melter apparatusembodiment 50, an embodiment similar to embodiment 1 illustratedschematically in FIGS. 1 and 2, except that melter exit structure 28 inembodiment 50 comprises a fluid-cooled end wall 33 and at least oneopening 52 in a bottom wall of melter exit structure 28. Melterapparatus embodiment 50 as illustrated has one opening 52, whichaccommodates one downwardly protruding melt flow tube 54. End wall 33effectively forces molten material to change flow direction, fromsubstantially horizontal to substantially vertically downward. This flowpattern completely decouples melt exit structure 28 and fluid-cooledtransition channel 30 from the conditioning channel (not illustrated),substantially reducing or completely eliminating transfer of allmechanical energy, such as vibrational energy, from the melter to thecondition channel, while maintaining all or substantially all of thedesired heat transfer.

FIG. 7 is a perspective view of a portion of a melter, melter exitstructure, skimmer, or dam illustrating two embodiments of fluid-cooledpanels useful in melter apparatus of the present disclosure. Alsoillustrated in FIG. 7 is a portion of melter floor 2, and threefloor-mounted burners 12. A first cooled-panel 130 is liquid-cooled,having one or more conduits or tubing 131 therein, supplied with liquidthrough conduit 132, with another conduit 133 discharging warmed liquid,routing heat transferred from inside the melter (or other componentbeing cooled) to the liquid away from the melter or other component.Liquid-cooled panel 130 as illustrated also includes a thin refractoryliner 135, which minimizes heat losses from the melter or othercomponent, but allows formation of a thin frozen glass shell to form onthe surfaces and prevent any refractory wear and associated glasscontamination. Another cooled panel 140 is illustrated, in this case anair-cooled panel, comprising a conduit 142 that has a first, smalldiameter section 144, and a large diameter section 146. Warmed airtransverses conduit 142 in the direction of the curved arrow. Conduitsection 146 is larger in diameter to accommodate expansion of the air asit warms. Air-cooled panels such as illustrated in FIG. 7 are describedmore fully in U.S. Pat. No. 6,244,197.

FIGS. 8, 9 and 10 are logic diagrams illustrating three methods inaccordance with the present disclosure. Embodiment 100 of FIG. 8includes the steps of feeding at least one partially vitrifiablematerial into a feed inlet of a melting zone of a melter vesselcomprising a floor, a ceiling, and a wall connecting the floor andceiling at a perimeter of the floor and ceiling, the melter vesselcomprising a batch feeder attached to the wall or ceiling and an exitend comprising a melter exit structure for discharging molten glass, themelter exit structure fluidly and mechanically connecting the meltervessel to a molten glass conditioning channel, box 102. The methodfurther includes heating the at least one partially vitrifiable materialwith at least one burner directing combustion products into the meltingzone under a level of the molten glass in the zone, and forming theturbulent molten glass while imparting mechanical energy to the meltervessel, box 104. The method also includes discharging molten glass fromthe melter vessel through a fluid-cooled transition channel of themelter exit structure, box 106, and cooling the fluid-cooled transitionchannel sufficiently to form a frozen glass layer or highly viscousglass layer on inner surfaces of the fluid-cooled transition channelthus protecting the melter exit structure from the mechanical energyimparted from the melter vessel to the melter exit structure, box 108.

FIG. 9 is a logic diagram of another method embodiment 200, whichincludes the steps of feeding at least one partially vitrifiablematerial into a feed inlet of a melting zone of a melter vesselcomprising a floor, a ceiling, and a wall connecting the floor andceiling at a perimeter of the floor and ceiling, the melter vesselcomprising a batch feeder attached to the wall or ceiling and an exitend comprising a melter exit structure for discharging molten glass, themelter exit structure fluidly and mechanically connecting the meltervessel to a molten glass conditioning channel, box 202, and heating theat least one partially vitrifiable material with at least one burnerdirecting combustion products into the melting zone under a level of themolten glass in the zone, and forming the turbulent molten glass whileimparting mechanical energy to the melter vessel, box 204. The methodalso includes discharging molten glass from the melter vessel through afluid-cooled transition channel of the melter exit structure, box 206,and cooling the fluid-cooled transition channel sufficiently to form afrozen glass layer or highly viscous glass layer on inner surfaces ofthe fluid-cooled transition channel thus protecting the melter exitstructure from the mechanical energy imparted from the melter vessel tothe melter exit structure, box 208. The method also includes flowing themolten glass from the melter vessel into the melter exit structure undera fluid-cooled skimmer extending downward from the ceiling of the meltervessel, the skimmer having a lower distal end defining a top of a throatof the melter vessel, box 210, and flowing the molten glass under alower distal end of the fluid-cooled skimmer extending a distancesubstantially greater than 12 inches (30 cm) below the level of thesubstantially molten glass, allowing molten glass in a bottom region ofthe melter vessel to exit the melting zone preferentially to moltenglass not substantially in the bottom region of the melter vessel, andtravel generally vertically upward through a relatively less turbulentzone prior to flowing generally horizontally out through thefluid-cooled transition channel of the melter exit structure, box 212.

FIG. 10 is a logic diagram of another method embodiment 300, whichincludes the steps of feeding at least one partially vitrifiablematerial into a feed inlet of a melting zone of a melter vesselcomprising a floor, a ceiling, and a wall connecting the floor andceiling at a perimeter of the floor and ceiling, the melter vesselcomprising a batch feeder attached to the wall or ceiling and an exitend comprising a melter exit structure for discharging molten glass, themelter exit structure fluidly and mechanically connecting the meltervessel to a molten glass conditioning channel, box 302, and heating theat least one partially vitrifiable material with at least one burnerdirecting combustion products into the melting zone under a level of themolten glass in the zone, and forming the turbulent molten glass whileimparting mechanical energy to the melter vessel, box 304. The methodalso includes discharging molten glass from the melter vessel through afluid-cooled transition channel of the melter exit structure, box 306,and cooling the fluid-cooled transition channel sufficiently to form afrozen glass layer or highly viscous glass layer on inner surfaces ofthe fluid-cooled transition channel thus protecting the melter exitstructure from the mechanical energy imparted from the melter vessel tothe melter exit structure, box 308. The method includes flowing themolten glass from the melter vessel into the melter exit structure undera fluid-cooled skimmer extending downward from the ceiling of the meltervessel, the skimmer having a lower distal end defining a top of a throatof the melter vessel, box 310, and flowing the molten glass through amolten glass outlet positioned at a bottom of the fluid-cooledtransition channel, causing molten glass flowing through the melter exitstructure to change direction from substantially horizontal tosubstantially vertically downward as it exits the channel, box 312.

In operation of melter apparatus of this disclosure, feed material, suchas E-glass batch (melts at about 1400° C.), insulation glass batch(melts at about 1200° C.), or scrap in the form of glass fiber matand/or insulation having high organic binder content, glass cullet, andthe like, is fed to the melter through a feeder 34 and melter inlet 5.One or more submerged combustion burners 12 are fired to melt the feedmaterials and to maintain a turbulent molten glass melt 14. Molten glassmoves toward melter exit structure 28, and is discharged from themelter. Combustion product gases (flue gases) exit through stack 8, ormay be routed to heat recovery apparatus, as discussed herein. Ifoxy-fuel combustion is employed in some or all burners, the generalprinciple is to operate combustion in the burners in a manner thatreplaces some of the air with a separate source of oxygen. The overallcombustion ratio may not change. Importantly, the throughput of melterapparatus described in the present disclosure may be 2 ft² per short tonper day (2 ft²/stpd) or less, and in some embodiments 0.5 ft²/stpd orless. This is at least twice, in certain embodiments ten times thethroughput of conventional melter apparatus.

Melter apparatus described in accordance with the present disclosure maybe constructed using only refractory cooled panels, and a thinrefractory lining, as discussed herein. The thin refractory coating maybe 1 centimeter, 2 centimeters, 3 centimeters or more in thickness,however, greater thickness may entail more expense without resultantgreater benefit. The refractory lining may be one or multiple layers.Alternatively, melters described herein may be constructed using castconcretes such as disclosed in U.S. Pat. No. 4,323,718. The thinrefractory linings discussed herein may comprise materials described inthe 718 patent, which is incorporated herein by reference. Two castconcrete layers are described in the 718 patent, the first being ahydraulically setting insulating composition (for example, that knownunder the trade designation CASTABLE BLOC-MIX-G, a product ofFleischmann Company, Frankfurt/Main, Federal Republic of Germany). Thiscomposition may be poured in a form of a wall section of desiredthickness, for example a layer 5 cm thick, or 10 cm, or greater. Thismaterial is allowed to set, followed by a second layer of ahydraulically setting refractory casting composition (such as that knownunder the trade designation RAPID BLOCK RG 158, a product of Fleischmanncompany, Frankfurt/Main, Federal Republic of Germany) may be appliedthereonto. Other suitable materials for the refractory cooled panels,melter refractory liners, and refractory block burners (if used) arefused zirconia (ZrO₂), fused cast AZS (alumina-zirconia-silica),rebonded AZS, or fused cast alumina (Al₂O₃). The choice of a particularmaterial is dictated among other parameters by the melter geometry andtype of glass to be produced.

Burners useful in the melter apparatus described herein include thosedescribed in U.S. Pat. Nos. 4,539,034; 3,170,781; 3,237,929; 3,260,587;3,606,825; 3,627,504; 3,738,792; 3,764,287; and 7,273,583, all of whichare incorporated herein by reference in their entirety. One usefulburner, for example, is described in the 583 patent as comprising amethod and apparatus providing heat energy to a bath of molten materialand simultaneously creating a well-mixed molten material. The burnerfunctions by firing a burning gaseous or liquid fuel-oxidant mixtureinto a volume of molten material. The burners described in the 583patent provide a stable flame at the point of injection of thefuel-oxidant mixture into the melt to prevent the formation of frozenmelt downstream as well as to prevent any resultant explosivecombustion; constant, reliable, and rapid ignition of the fuel-oxidantmixture such that the mixture burns quickly inside the molten materialand releases the heat of combustion into the melt; and completion of thecombustion process in bubbles rising to the surface of the melt. In oneembodiment, the burners described in the 583 patent comprises an innerfluid supply tube having a first fluid inlet end and a first fluidoutlet end and an outer fluid supply tube having a second fluid inletend and a second fluid outlet end coaxially disposed around the innerfluid supply tube and forming an annular space between the inner fluidsupply tube and the outer fluid supply tube. A burner nozzle isconnected to the first fluid outlet end of the inner fluid supply tube.The outer fluid supply tube is arranged such that the second fluidoutlet end extends beyond the first fluid outlet end, creating, ineffect, a combustion space or chamber bounded by the outlet to theburner nozzle and the extended portion of the outer fluid supply tube.The burner nozzle is sized with an outside diameter corresponding to theinside diameter of the outer fluid supply tube and forms a centralizedopening in fluid communication with the inner fluid supply tube and atleast one peripheral longitudinally oriented opening in fluidcommunication with the annular space between the inner and outer fluidsupply tubes. In certain embodiments, a longitudinally adjustable rod isdisposed within the inner fluid supply tube having one end proximate thefirst fluid outlet end. As the adjustable rod is moved within the innerfluid supply tube, the flow characteristics of fluid through the innerfluid supply tube are modified. A cylindrical flame stabilizer elementis attached to the second fluid outlet end. The stable flame is achievedby supplying oxidant to the combustion chamber through one or more ofthe openings located on the periphery of the burner nozzle, supplyingfuel through the centralized opening of the burner nozzle, andcontrolling the development of a self-controlled flow disturbance zoneby freezing melt on the top of the cylindrical flame stabilizer element.The location of the injection point for the fuel-oxidant mixture belowthe surface of the melting material enhances mixing of the componentsbeing melted and increases homogeneity of the melt. Thermal NO_(x)emissions are greatly reduced due to the lower flame temperaturesresulting from the melt-quenched flame and further due to insulation ofthe high temperature flame from the atmosphere.

Melter apparatus in accordance with the present disclosure may alsocomprise one or more wall-mounted submerged combustion burners, and/orone or more roof-mounted burners. Roof-mounted burners may be useful topre-heat the melter apparatus melting zone 14 and serve as ignitionsources for one or more submerged combustion burners 12. Melterapparatus having only wall-mounted, submerged-combustion burners arealso considered within the present disclosure. Roof-mounted burners maybe oxy-fuel burners, but as they are only used in certain situations,are more likely to be air/fuel burners. Most often they would beshut-off after pre-heating the melter and/or after starting one or moresubmerged combustion burners 12. In certain embodiments, if there is apossibility of carryover of batch particles to the exhaust, one or moreroof-mounted burners could be used to form a curtain to preventparticulate carryover. In certain embodiments, all submerged combustionburners 12 are oxy-fuel burners (where “oxy” means oxygen, oroxygen-enriched air, as described earlier), but this is not necessarilyso in all embodiments; some or all of the submerged combustion burnersmay be air-fuel burners. Furthermore, heating may be supplemented byelectrical heating in certain embodiments, in certain melter zones.

The total quantities of fuel and oxidant used by the combustion systemare such that the flow of oxygen may range from about 0.9 to about 1.2of the theoretical stoichiometric flow of oxygen necessary to obtain thecomplete combustion of the fuel flow. Another expression of thisstatement is that the combustion ratio is between 0.9 and 1.2. Incertain embodiments, the equivalent fuel content of the feed materialmust be taken into account. For example, organic binders in glass fibermat scrap materials will increase the oxidant requirement above thatrequired strictly for fuel being combusted. In consideration of theseembodiments, the combustion ratio may be increased above 1.2, forexample to 1.5, or to 2, or 2.5, or even higher, depending on theorganic content of the feed materials.

The velocity of the fuel in the various burners depends on the burnergeometry used, but generally is at least about 15 m/s. The upper limitof fuel velocity depends primarily on the desired mixing of the melt inthe melter apparatus, melter geometry, and the geometry of the burner;if the fuel velocity is too low, the flame temperature may be too low,providing inadequate melting, which is not desired, and if the fuel flowis too high, flame might impinge on the melter floor, roof or wall,and/or heat will be wasted, which is also not desired, and/or the degreeof turbulence may so great as to be detrimental to refractory, or othermaterials of construction. High turbulence may also produce an undesiredamount of foam or bubbles in the melt that cannot be refined out of themelt if the conditioning facilities are not adequate.

In certain embodiments of the disclosure it may be desired to implementheat recovery. In embodiments of the disclosure employing a heattransfer fluid for heat recovery, it is possible for a hot intermediateheat transfer fluid to transfer heat to the oxidant or the fuel eitherindirectly by transferring heat through the walls of a heat exchanger,or a portion of the hot intermediate fluid could exchange heat directlyby mixing with the oxidant or the fuel. In most cases, the heat transferwill be more economical and safer if the heat transfer is indirect, inother words by use of a heat exchanger where the intermediate fluid doesnot mix with the oxidant or the fuel, but it is important to note thatboth means of exchanging heat are contemplated. Furthermore, theintermediate fluid could be heated by the hot flue gases by either ofthe two mechanisms just mentioned.

In certain embodiments employing heat recovery, the primary means fortransferring heat may comprise one or more heat exchangers selected fromthe group consisting of ceramic heat exchangers, known in the industryas ceramic recuperators, and metallic heat exchangers further referredto as metallic recuperators. Apparatus and methods in accordance withthe present disclosure include those wherein the primary means fortransferring heat are double shell radiation recuperators. Preheatermeans useful in apparatus and methods described herein may comprise heatexchangers selected from ceramic heat exchangers, metallic heatexchangers, regenerative means alternatively heated by the flow of hotintermediate fluid and cooled by the flow of oxidant or fuel that isheated thereby, and combinations thereof. In the case of regenerativemeans alternately heated by the flow of hot intermediate fluid andcooled by the flow of oxidant or fuel, there may be present two vesselscontaining an inert media, such as ceramic balls or pebbles. One vesselis used in a regeneration mode, wherein the ceramic balls, pebbles orother inert media are heated by hot intermediate fluid, while the otheris used during an operational mode to contact the fuel or oxidant inorder to transfer heat from the hot media to the fuel or oxidant, as thecase might be. The flow to the vessels is then switched at anappropriate time.

Melter apparatus and process embodiments of the disclosure may becontrolled by one or more controllers. For example, burner combustion(flame) temperature may be controlled by monitoring one or moreparameters selected from velocity of the fuel, velocity of the primaryoxidant, mass and/or volume flow rate of the fuel, mass and/or volumeflow rate of the primary oxidant, energy content of the fuel,temperature of the fuel as it enters the burner, temperature of theprimary oxidant as it enters the burner, temperature of the effluent,pressure of the primary oxidant entering the burner, humidity of theoxidant, burner geometry, combustion ratio, and combinations thereof.Exemplary apparatus and methods of the disclosure comprise a combustioncontroller which receives one or more input parameters selected fromvelocity of the fuel, velocity of the primary oxidant, mass and/orvolume flow rate of the fuel, mass and/or volume flow rate of theprimary oxidant, energy content of the fuel, temperature of the fuel asit enters the burner, temperature of the primary oxidant as it entersthe burner, pressure of the oxidant entering the burner, humidity of theoxidant, burner geometry, oxidation ratio, temperature of the effluentand combinations thereof, and employs a control algorithm to controlcombustion temperature based on one or more of these input parameters.

The burners used may provide an amount of heat which is effective tomelt the initial raw material to form the molten material 14, and tomaintain the molten material 14 in its molten state. The optimaltemperature for melting the initial raw material and maintaining themolten material 14 in its molten state can depend on, for example, thecomposition of the initial raw material and the rate at which the moltenmaterial 14 is removed from the melter apparatus. For example, themaximum temperature in the melter apparatus can be at least about 1400°C., preferably from about 1400° C. to about 1650° C. The temperature ofthe molten material 14 can be from about 1050° C. to about 1450° C.;however, apparatus and methods of the present disclosure are not limitedto operation within the above temperature ranges. The molten material 14removed from the melter apparatus is typically a substantiallyhomogeneous composition, but is not limited thereto.

Although only a few exemplary embodiments of this disclosure have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel apparatus andprocesses described herein. Accordingly, all such modifications areintended to be included within the scope of this disclosure as definedin the following claims. In the claims, no clauses are intended to be inthe means-plus-function format allowed by 35 U.S.C. §112, paragraph 6unless “means for” is explicitly recited together with an associatedfunction. “Means for” clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents, but also equivalent structures.

What is claimed is:
 1. A method comprising: a) feeding at least onepartially vitrifiable material into a feed inlet of a melting zone of amelter vessel comprising a floor, a ceiling, and a wall connecting thefloor and ceiling at a perimeter of the floor and ceiling, the meltervessel comprising a batch feeder attached to the wall or ceiling and anexit end comprising a melter exit structure for discharging moltenglass, the melter exit structure fluidly and mechanically connecting themelter vessel to a molten glass conditioning channel, the wallcomprising a feed end wall, a first portion of an exit end wallconnecting the floor to an inlet of the melter exit structure, and asecond portion of an exit end wall connecting the ceiling to an inlet ofthe melter exit structure, wherein the feed end wall forms an angle αwith the floor, the first portion of the exit end wall forms an angle βwith the floor, angles α and β may be the same or different and rangefrom about 45 degrees to about 75 degrees and the second portion of theexit wall forms an angle γ with the ceiling ranging from about 30degrees to about 75 degrees; b) heating the at least one partiallyvitrifiable material with at least one burner directing combustionproducts into the melting zone under a level of the molten glass in thezone, and forming the turbulent molten glass while imparting mechanicalenergy to the melter vessel; c) discharging molten glass from the meltervessel through a fluid-cooled transition channel of the melter exitstructure; and d) cooling the fluid-cooled transition channelsufficiently to form a frozen glass layer or highly viscous glass layer,or combination thereof, on inner surfaces of the fluid-cooled transitionchannel thus protecting the melter exit structure from the mechanicalenergy imparted from the melter vessel to the melter exit structure. 2.The method of claim 1 further comprising at least partially damming thefluid-cooled transition channel by moving a movable fluid-cooled damthrough a fluid-cooled dam opening in a top of the fluid-cooledtransition channel.
 3. The method of claim 2 comprising extending thedam an entire distance from top to bottom of the fluid-cooled transitionchannel and completely isolating the melting zone of the melter vesselfrom the conditioning channel.
 4. The method of claim 1 comprisingflowing the molten glass from the melter vessel into the melter exitstructure under a fluid-cooled skimmer configured to form a frozen glasslayer or highly viscous glass layer, or combination thereof, on outersurfaces thereof, the skimmer extending downward from the ceiling of themelter vessel, the skimmer having a lower distal end defining a top of athroat of the melter vessel.
 5. The method of claim 4 wherein theflowing of the molten glass from the melter vessel into the melter exitstructure under a fluid-cooled skimmer comprises flowing the moltenglass under a lower distal end of the fluid-cooled skimmer extending adistance ranging from about 1 inch to about 12 inches (from about 2.5 cmto about 30 cm) but less than a height H of the melter exit structure.6. The method of claim 4 wherein flowing of the molten glass from themelter vessel into the melter exit structure under a fluid-cooledskimmer comprises flowing the molten glass under a lower distal end ofthe fluid-cooled skimmer extending a distance substantially greater than12 inches (30 cm) but less than to the floor of the melter, allowingmolten glass in a bottom region of the melter vessel to exit the meltingzone preferentially to molten glass not substantially in the bottomregion of the melter vessel, and travel generally vertically upwardthrough a relatively less turbulent zone prior to flowing generallyhorizontally out through the fluid-cooled transition channel of themelter exit structure.
 7. The method of claim 4 wherein flowing of themolten glass from the melter vessel into the melter exit structurecomprises flowing the molten glass through a seamless liner insertpositioned inside the melter exit structure, the liner insert having anentrance and a discharge end, the entrance end accepting flow of moltenglass from the throat, and the discharge end directing flow of moltenglass to the conditioning channel.
 8. The method of claim 1 whereinflowing of the molten glass from the melter vessel into the melter exitstructure comprises flowing the molten glass through a molten glassoutlet positioned at a bottom of the fluid-cooled transition channel,causing molten glass flowing through the melter exit structure to changedirection from substantially horizontal to substantially verticallydownward as it exits the channel.